WIP: Cleanup tests

[NOhs]

Moving to pytest for better test output and less verbose test writing.
Starting to add more than just a few example tests.

[codecov]

Codecov Report

Merging #115 into master will decrease coverage by 2.64%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #115      +/-   ##
==========================================
- Coverage   78.54%   75.89%   -2.65%     
==========================================
  Files          17       17              
  Lines        1193     1174      -19     
==========================================
- Hits          937      891      -46     
- Misses        256      283      +27     

Impacted Files	Coverage Δ
clang_build/build_type.py	92.85% <100.00%> (+19.52%)	⬆️
clang_build/clang_build.py	56.25% <100.00%> (+1.99%)	⬆️
clang_build/compiler.py	68.08% <100.00%> (-19.15%)	⬇️
clang_build/directories.py	100.00% <100.00%> (ø)
clang_build/platform.py	38.29% <0.00%> (-29.79%)	⬇️
clang_build/project.py	79.71% <0.00%> (-4.86%)	⬇️
clang_build/target.py	78.24% <0.00%> (-1.32%)	⬇️
clang_build/progress_bar.py	82.22% <0.00%> (+2.22%)	⬆️
... and 2 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 270f775...4addf6b. Read the comment docs.